This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The purpose of this study is to determine how common low levels of magnesium are in patients with end stage liver disease. In addition, the study will try to determine if low levels of Mg affect the release of PTH in patients with end stage liver disease and low vitamin D levels.